Main topology is about the same as AX1200, which is a 2-phase interleaved CCM-PFC stage, followed by a 2-stage DC-DC converter. The first stage is a buck pre-regulator stage, and the second stage is a 2-phase interleaved LLC-HB resonant converter (with secondary SR) working in fixed-frequency fixed-duty mode which provides the isolation between primary and secondary and the voltage step-down. The 2-stage 12V converter is controlled by a UC3843 current-mode PWM controller. The minor rails DC-DC and standby circuit are traditional designs controlled by analog controllers. The interleaved CCM-PFC is controlled by the DSP on the primary side, while the two MCUs on the secondary side take care of the fan control, housekeeping functions and USB communications to the host. In a nutshell, AX1200i is AX1200 equipped with digitalized interleaving PFC stage and digital supervisory chips.

In the test, AX1200i exhibited amazing voltage regulations on all major rails, very high efficiency, very fast transient response on +12V output but lackluster response on minor rails.

Doesn't that carry a great potential for unbalancing regulation, because of the much lower ESR and usually a significantly lower capacity? I believe there are cases where unwanted resonance can occur because the original engineering team didn't count on such drastically different values, causing worse performance, or even a protection IC enforced shutdown.

Doesn't that carry a great potential for unbalancing regulation, because of the much lower ESR and usually a significantly lower capacity? I believe there are cases where unwanted resonance can occur because the original engineering team didn't count on such drastically different values, causing worse performance, or even a protection IC enforced shutdown.

When guryhwa recaps a PSU, or designs a PSU with all-polymer output filter, he knows what he's doing. Closed-loop stability must be ensured before you pursue low ripple and fast response. A main reason he uses ULR is because it can provide similar capacity as Al-e caps.